Select and view full activity log text in a pop-up

[iTerminate]

Summary

• V opens a browse popup over the activity log's retained entries (from both the main table's docked panel and the fullscreen graph's) — a scrollable list of lines plus a detail pane showing the highlighted entry's full, untruncated text (timestamp, name, detail, entity_id)
• Adds format_log_datetime/format_log_detail in logbook.py and exposes ActivityLogPanel.entries/title_text for the popup to consume
• Closes Select and view full activity log text in a pop-up #23

Test plan

• pytest full suite (1231 passed)
• uv run pyright / uv run ruff check . clean
• Manual smoke in --demo mode: a → V on the main table and on the fullscreen graph (G → a → V), confirmed the popup renders, the detail pane tracks the highlight, and escape returns to the still-open log panel

https://claude.ai/code/session_0183tLCjQihNP7X2cXECuh2n